Help Please - re-jet 454 merc carb
#12
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Well, opened up my carb to get at thge jets and weird enough all 4 were different. The two front primary's were close (.113 & .101) but still different, where the 2 secondary were very different in diameter (.098 & .077)
Took them to Mopak that carries Edelbrock jets and rods. Unfortunately I'm not sure of the knowledge of their "carb expert" or whether he steered me in the wrong direction. He wasn't able to confirm my carb (even though I gave him the 9772S number), so he went off a 1410 Edelbrock. I explained I bought the bought from Phoenix and needed it leaned out. In the end he gave me part #1431 for primary (.107) with part# 1445 rods, and 1429 (.101) for secondary. I'm questioning his knowledge cause for the longest time he kept ca;ling the 1431 primaries a secondary jet and spent 20 minutes finding me new primaries. It wasn't until I got home that I realized he was mixing up the secondary and primary jets - I called him and he said to ensure the 1431 go with the 1445 rods, so in the end I used the 1431 for primary and the 1429 for secondary (I think though he was expecting the diameters of the two to be opposite, so not sure if it is optimized). At least I have matching sets though now on each side.
Put it back together and it fired up nice on the hose. Revs nice. Haven't water tested it yet cause I think I first need it properly timed.
Will provide an update after timing is set and water tested.
Thanks
Took them to Mopak that carries Edelbrock jets and rods. Unfortunately I'm not sure of the knowledge of their "carb expert" or whether he steered me in the wrong direction. He wasn't able to confirm my carb (even though I gave him the 9772S number), so he went off a 1410 Edelbrock. I explained I bought the bought from Phoenix and needed it leaned out. In the end he gave me part #1431 for primary (.107) with part# 1445 rods, and 1429 (.101) for secondary. I'm questioning his knowledge cause for the longest time he kept ca;ling the 1431 primaries a secondary jet and spent 20 minutes finding me new primaries. It wasn't until I got home that I realized he was mixing up the secondary and primary jets - I called him and he said to ensure the 1431 go with the 1445 rods, so in the end I used the 1431 for primary and the 1429 for secondary (I think though he was expecting the diameters of the two to be opposite, so not sure if it is optimized). At least I have matching sets though now on each side.
Put it back together and it fired up nice on the hose. Revs nice. Haven't water tested it yet cause I think I first need it properly timed.
Will provide an update after timing is set and water tested.
Thanks
Last edited by dna; 07-11-2015 at 07:44 PM.
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Thanks
#15
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If serial number for your 1992 454 falls in this range - 0D805069-thru-0F304999. Below is an exploded view and parts list for the Weber carb. Model 9772S primary jets were .107 (#811541). Secondary jets were .98 (#811542).
http://www.marineengine.com/parts/me...rburetor-weber
http://www.marineengine.com/parts/me...rburetor-weber
#18
The link was very useful. Only issue is that I really didn't have a good base, being that I had 4 different jets. The charts in the link show a 'base' and then explain how to adjust based on altitude change. Based on what I had, what do you think of the new jets and rods I got - do you think it will be an improvement? I guess one way to tell is from the plugs after I have been running them for a while.
Thanks
Thanks
Secondary jet: 1430, .104
Primary jet: 1433, .113
Rod: 1457. .073x.052
#19
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Here are the specs on the stock carb jetting/rods/etc as delivered by Mercruiser:
Page 2;
http://www.boatfix.com/merc/bullet/91/91_06.PDF
Page 2;
http://www.boatfix.com/merc/bullet/91/91_06.PDF